Wireless communication apparatus, a method of wireless communication, and a program for wireless communication

ABSTRACT

In wireless communication with another communication apparatus in a predetermined wireless network, overhead information defined in a media access control layer is divided into a header of information necessary for the common access control and a header of information necessary for each payload. Address information is added to the header of information necessary for the common access control to transmit the generated header attached to the transmission data. For example, in a case of forming a physical burst in which a plurality of data payloads are combined into one, a frame structure is provided without useless repetition of address information.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/290,143, filed on May 29, 2014, which is a continuation of U.S.application Ser. No. 13/941,952, filed on Jul. 15, 2013 (U.S. Pat. No.8,792,400), which is a continuation of U.S. application Ser. No.12/781,370, filed on May 17, 2010 (U.S. Pat. No. 8,711,742), which is acontinuation of U.S. application Ser. No. 10/834,798, filed on Apr. 29,2004 (U.S. Pat. No. 7,746,842), which is based on Japanese PriorityDocument JP 2003-139547, filed in the Japanese Patent Office on May 16,2003, the disclosures of which are being incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a communication apparatus, a method ofcommunication, and a program executing a process for communication,which are preferably applicable to, for example, a wireless LAN (LocalArea Network) system for data communication.

2. Description of Related Art

Conventionally, in wireless communication in which a predeterminedtransmission unit of packets are collectively transmitted, it is generalthat a structure of packet information of each transmission unit isdetermined in advance and the packet information is added to each packetto be transmitted.

On the other hand, in a rate variable transmission method for a generalwireless communication system, it is known that transmission is carriedout by a mechanism called fall back at a possible highest rate. When anerror occurs, the transmission rate is decreased to a predeterminedtransmission rate for re-transmission.

In a rate variable control method for these wireless communicationsystems, there was proposed one in which header information includesrate information regarding a modulation process of a payload portion onthe basis of a predetermined frame format. In the method, in a casewhere the header information can be decoded, a desired payload portionis decoded at a rate that is changed to the rate of the modulationprocess.

Here, in the conventional wireless communication system, a possibletransmission rate is substantially determined in accordance with abandwidth of a signal used in the wireless communication.

That is, in a certain wireless communication system, since a data ratefor transmitting an application is substantially determined inaccordance with its bandwidth. For example, an IEEE (The Institute ofElectrical and Electronics Engineers) 802.11b-compliant wirelesscommunication system has been designed to use a data rate of severalmegabits/sec and an IEEE 802.11a-compliant wireless communication systemhas been designed to use a data rate of tens megabits/sec.

Therefore, a fragment process and a frame structure, optimized for eachwireless communication system, are specially prepared as a uniquestructure for each system.

FIG. 18 illustrates a MAC header structure defined in a small power datacommunication system/wireless 1394 system (ARIB STD-T72) (at page 102 ofthe standard book) as an existent data frame example.

The MAC header of this wireless communication system includesinformation such as a packet type, a transmission source station ID, atransmission destination station ID, a relay station ID, a B/E flag, asequence number, and a data length (Length).

In such an existing wireless communication system, the MAC headerinformation is formed in which information pieces of address informationsuch as a destination and a transmission source, a sequence number, adata length, and presence and absence of a fragment are mixed.

FIG. 19 illustrates a MAC header and a frame body according to a frameformat defined by the IEEE Draft P802.15.3/D16 standard (page 109) as anexemplary data frame structure of the existing technology according toRelated Art.

In the figure, a MAC header includes a Frame Control (two Octets), a PNID (two Octets), a Destination DEV ID (one Octet), a Source DEV ID (oneOctet), a Fragmentation Control (three Octets), and a Stream Index (oneOctet).

This case features that all address information pieces are representedby a DEV ID (device identifier). Further, contents of a predeterminedfragment process are represented by a predetermined bit at aFragmentation control field. In addition to the MAC header, a Frame Body(variable length) as a data payload and an FCS (4 Octets) for errordetection constitutes a frame. Though it is not shown between the MACheader and the MAC frame in the figure, a header check sequence (HCS)may be further provided.

FIG. 20 illustrates a frame format defined by the IEEE Std 802.11, 1999edition (at page 34) as an example of an existing data frame structure.

The MAC header includes a Frame Control (two Octets), a Duration ID (twoOctets), an Address 1 (six Octets), an Address 2 (six Octets), anAddress 3 (six Octets), a Sequence Control (two Octets), and an Address4 (six Octets). In addition, a frame body (0-2312 Octets) as a datapayload and FCS (four Octets) are also included therein.

Address fields of the Address 1 to the Address 4 in this configurationare occasionally assigned to a source address, a destination address, orthe like, if necessary. Further, sequence number information and thelike are described at the Sequence Control field.

FIG. 21 shows a fragment structure defined in the IEEE Std 802.11, 1999edition (page 71) as an example of an existing fragmentation process.

In this fragment structure, a predetermined MSDU is divided into fourfragments, namely, Fragment 0 to Fragment 3. A MAC header and a CRC(Cyclic Redundancy Check) are added to each fragment. It is understoodthat, when the fragmentation process is executed, MAC header informationis attached to each fragment.

FIG. 22 shows an example in which a plurality of MAC frame informationpieces are formed in one PHY burst according to a related art technique.This shows that the sequences #1 to #3 are combined to form a singleburst with once generated MAC header and FCS (CRC) attached thereto.That is, there exists each MAC header of the sequences #1 to #3 beingmultiplexed.

It is also understood that even if such a data frame format is adopted,a sequence number and fragment information of a data payload arenecessary for each sequence, but the reception destination addressinformation and the transmission source address information and the likeare commonly used.

The Patent Document 1 cited below discloses an example of such a headerstructure.

[Patent Document 1]

Japanese Patent Application Publication No. Hei 10-247942

As described above, in the related art frame format, the MAC headers aregenerally multiplexed as they are. Thus, there is a problem thatredundant fields such as address information exist at the MAC headermore than the necessity.

Further, in a case where a predetermined transmission unit of packetsare transmitted collectively, the same information such as addressinformation is included as header information during transmission ateach packet. Thus, there is a problem that such header informationbecomes redundant.

SUMMARY OF THE INVENTION

In view of the problem described above, the present invention provideseffective packet construction suitable for a case of employing acommunication system such as a wireless LAN system.

According to an aspect of the present invention, in a case of wirelesscommunication with another communication apparatus through apredetermined wireless communication network, overhead informationdefined at a media access control layer is divided into a first headerincluding data necessary for common access control and a second headerincluding data necessary for each payload, in which address informationis added to the first header including the data necessary for the commonaccess control, and the generated headers are added to transmission datafor transmission.

For example, in a case of forming a physical burst (PHY burst) with aplurality of data payloads combined into one, this structure provides aframe configuration without useless repetition of the addressinformation.

According to the present invention, overhead information defined in aMAC layer is formed with a single piece of common MAC header informationand a sub-MAC header in a frame structure. This efficiently provides adata frame and a corresponding control information frame.

In addition, in a case of transmitting a plurality of data payloads inthe form of a single frame (burst), only the sub-MAC header is added toeach payload, which results in configuration of a frame with minimumrequirement parameters.

Further, since a frame is formed with portions (a PHY header and thecommon MAC header) transmitted at a known fixed transmission rate andthe other portions (the sub-MAC header and the data payload) transmittedat a variable transmission rate, in a case where a plurality of framesare sequentially connected to form a frame, a transmission frame can beprovided with compression for overlapped information in the MAC headerinformation.

In addition, since the address information is described at the commonMAC header, and its error detection code is added thereto, only theinformation of which address can be correctly decoded is instantaneouslyobtained.

Still furthermore, length information and a sequence number of the datapayload length, a sequence number, and fragment information are added tothe sub-MAC header, so that the information in the common MAC header isallowed to include only minimum requirement information.

Furthermore, at the PHY header, rate information used for the datapayload is informed, so that a margin can be provided for a timeinterval from when the rate is specified until the rate is actuallychanged.

In addition, fragmentation process in which the data payload formedusing the sub-MAC header is fragmented at a predetermined lengthprovides a suitable frame structure for cases using various ARQ methods.

Since the description of the fragment unit at the common MAC headerprevents the error from affecting the later part, even in a case wherethere is an error in the data, thus providing a frame structureefficient, for example, for the selectively repeat ARQ.

Forming the common MAC headers in the same configuration between acontrol information frame and a data frame provides easy multiplexing,so that a single burst can be simply formed.

Forming the control information frame in the predetermined common MACheader structure makes multiplexing a plurality of control informationframes easy, so that a single burst can be simply formed.

BRIEF DESCRIPTION OF THE DRAWINGS

The object and features of the present invention will become morereadily apparent from the following detailed description taken inconjunction with the accompanying drawings and the same or correspondingelements or parts are designated with like references throughout thedrawings in which:

FIG. 1 is an illustration showing an example of a wireless networkconfiguration according to an embodiment of the present invention;

FIG. 2 is a block diagram of an exemplary wireless communicationapparatus according to the embodiment of the present invention;

FIG. 3 is a time chart illustrating an exemplary transmission superframe period according to the embodiment of the present invention;

FIGS. 4A and 4B is a time chart illustrating an exemplary datatransmission sequence according to the embodiment of the presentinvention;

FIG. 5 is an illustration describing an outline of a frame formataccording to the embodiment of the present invention;

FIG. 6 is an illustration describing an exemplary data frame formataccording to the embodiment of the present invention;

FIG. 7 is an illustration describing an exemplary multiplexed data frameformat according to the embodiment of the present invention;

FIG. 8 is an illustration describing an exemplary fragmented data frameformat according to the embodiment of the present invention;

FIG. 9 is an illustration describing an exemplary ACK frame formataccording to the embodiment of the present invention;

FIG. 10 is an illustration describing an exemplary RTS frame formataccording to the embodiment of the present invention;

FIG. 11 is an illustration describing an exemplary CTS frame formataccording to the embodiment of the present invention;

FIG. 12 is an illustration describing an exemplary format of the controlframe+the data frame according to the embodiment of the presentinvention;

FIG. 13 is an illustration describing an exemplary format of a controlframe+a control frame according to the embodiment of the presentinvention;

FIG. 14 is a flow chart showing an exemplary operation of thecommunication apparatus according to the embodiment of the presentinvention;

FIG. 15 is a flow chart showing an exemplary header setting process ofthe communication apparatus according to the embodiment of the presentinvention;

FIG. 16 is a flow chart showing an exemplary transmission activationprocess of the communication apparatus according to the embodiment ofthe present invention;

FIG. 17 is a flow chart showing an exemplary communication process ofthe communication apparatus according to the embodiment of the presentinvention;

FIG. 18 is an illustration describing an MAC header according to relatedart;

FIG. 19 is an illustration showing an example of a MAC header and bodyframe format according to related art;

FIG. 20 is an illustration showing an example of a MAC header and bodyframe format according to related art;

FIG. 21 is an illustration showing an example of a MAC header and bodyframe format according to related art; and

FIG. 22 is an illustration showing an example of a MAC header and bodyframe format according to related art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of the present embodiment will be described below withreference to FIGS. 1 to 17.

This embodiment assumes that a propagation path of communication iswireless and that a network is formed among a plurality of apparatuseswith a single transmission medium (a link is not divided with frequencychannels). However, if a plurality of frequency channels exist as atransmission medium, the same result can be achieved also. Further, thecommunication assumed in this embodiment is a stored and forward typetraffic in which information is transmitted in a packet unit. Further,the network according to this embodiment is an ad hoc network in whichthere is no control station for controlling overall stations in thenetwork. However, the present invention is applicable to a networkincluding a control station, as mentioned later.

FIG. 1 shows an exemplary arrangement of communication apparatuses(communication stations) forming a wireless communication systemaccording to the embodiment of the present invention. This illustratesthat seven communication apparatuses 1, 2, - - - 7 are distributed in asingle space.

In FIG. 1, communication areas 1 a, 2 a, - - - , and 7 a of thecommunication apparatuses 1, 2, - - - , and 7, respectively, are denotedwith chain lines. It is defined that each area in which each of thecommunication apparatuses is communicable with other communicationapparatuses existing within the area and also causes interference withits own transmission in the area, as follows:

The communication apparatus 1 exits in an area communicable with theadjacent communication apparatuses 2, 3, and 7.

The communication apparatus 2 exits at in area communicable with theadjacent communication apparatuses 1 and 3.

The communication apparatus 3 exits in an area communicable with theadjacent communication apparatuses 1, 2, and 5.

The communication apparatus 4 exits in an area communicable with theadjacent communication apparatus 5.

The communication apparatus 5 exits in an area communicable with theadjacent communication apparatuses 3, 4, and 6.

The communication apparatus 6 exits in an area communicable with theadjacent communication apparatus 5.

The communication apparatus 7 exits in an area communicable with theadjacent communication apparatus 1.

In this embodiment, each communication apparatus performs an accesscontrol process in which one wireless transmission path istime-divisionally used with consideration of influence among thecommunication apparatus and the adjacent other communicationapparatuses.

FIG. 2 is a block diagram of each wireless communication apparatus as acommunication station in this exemplary system. This wirelesscommunication apparatus includes an interface 11 for exchanging variousinformation with a device (not shown) coupled to this wirelesscommunication apparatus, and a data buffer 12 for temporarily storingthe data transmitted from the connected device through the interface 11and the data received through the wireless transmission path.

The wireless communication apparatus further includes a central controlsection 10 for unitedly effecting control of both a sequentialinformation transmission and reception process and an access control ofthe transmission path. The wireless communication apparatus furtherincludes a burst generation section 13 for generating a frame burst fromthe transmission data as a processing section executing transmissionprocess under the control of the central control section 10, a commonheader information and control information generation section 14 forgenerating a common MAC header information and control information, anda wireless transmission section 16 for transmitting these information.The burst generation section 13 of the present example includes asub-header generation section 13 a for generating sub-header informationin a predetermined unit. A preamble specified by a preamble insertionsection 17 is inserted into a packet to be transmitted by the wirelesstransmission section 16.

The wireless communication apparatus further includes, as a processingsection for a reception process under the control by the central controlsection 10, a wireless reception section 20 receiving an receptionsignal, a common header information/control information analyzingsection 21 for analyzing the common header information and the controlinformation in the signal received by the wireless reception section 20,and a burst analyzing section 22. Reception in the wireless receptionsection 20 is executed at a timing depending the detection of a preamblein a preamble detection section 19.

Transmission process in the wireless transmission section 16 andreception process in the wireless reception section 20 are performed ata timing under control of an access control section 15, respectively.The wireless transmission section 16 executes a modulation process, forexample, for an Ultra Wideband (UWB) signal on a signal to betransmitted. The wireless reception section 20 executes a demodulationprocess, for example, for the Ultra Wideband (UWB) signal on a receivedsignal and supplies demodulated data to a later stage of a circuit. Anantenna 18 for transmitting and receiving a wireless signal is coupledto the wireless transmission section 16 and the wireless receptionsection 20. Here, it is also possible to prepare individual antennas forthe transmission and the reception, respectively. Further, it is alsopossible to prepare a plurality of antennas to provide so-calleddiversity reception.

A common header information/control information analyzing section 21extracts a common header section from the received signal and analyzesit. The burst analyzing section 22 analyzes the structure of a receiveddata burst from the received common header information. The burstanalyzing section 22 further includes a sub-header analyzing section 22a for analyzing sub-headers in the received data burst. The burstanalyzing section 22 recognizes the data received in a sub-header unitand includes an ACK information generation section 23 for generating ACKinformation indicative of the reception confirmation. An informationstoring section 24 is further coupled to the central control section 10,as storing regions of the information storing section 24, an accesscontrol information storing section 24 a and a rate information storingsection 24 b necessary for constituting the burst.

The above description is made with an example of the UWB system as awireless communication system. However, it is also possible to use othervarious communication systems applicable, for example, to a wirelessLAN, and suitable for communication having a relative near fieldcommunication. More specifically, as a system other than the UWB system,the OFDM (Orthogonal Frequency Division Multiplex) method, the CDMA(Code Division Multiple Access) method, and the like are applicable.

Next, transmission conditions at the wireless communication apparatusesin the network of this example will be described with reference to FIGS.3 to 13. FIG. 3 shows an exemplary frame configuration (a unit oftransmission super frame period) adopted in the system of this example.In this example, one super frame period is defined by transmission of abeacon signal B from each wireless communication apparatus, and the sameperiod and a different offset timing are set for each wirelesscommunication apparatus. That is, setting a beacon transmission positionin each wireless communication apparatus different from any otherwireless communication apparatus forms a self-organized distributed typeof ad hoc wireless network. Transmitting a beacon signal B from awireless communication apparatus provides a self-receiving region for apredetermined interval from the transmission to this wirelesscommunication system.

FIG. 4A and FIG. 4B show an example of a data transmission sequenceaccording to the RTS/CTS control in this example. This shows a sequencein which a data frame is transmitted from a transmission sourceapparatus (Tx device (FIG. 4A)) to a reception destination apparatus (Rxdevice (FIG. 4B)).

In this example, the transmission source apparatus transmits a requestto send RTS to the reception destination apparatus. After a lapse of apredetermined interval SIFS, the reception destination apparatus returnsa confirmation notice CTS to the transmission source apparatus. After alapse of a predetermined interval SIFS, the transmission sourceapparatus transmits a data frame to the reception destination apparatus.After a lapse of a predetermined interval SIFS, the receptiondestination apparatus returns an acknowledge ACK to the transmissionsource apparatus.

FIG. 5 shows an outline of a data frame structure of this example. Inthis example, a common MAC (Media Access Control) header is arrangedsubsequent to a PHY header as a physical header. A header check sequence(HCS) for the common MAC header is arranged subsequent thereto. Further,after this, a sub-MAC header, a data payload, a frame check sequence(FCS) are arranged. Here, the PHY header, the common MAC header, and theHCS are transmitted at a fixed transmission rate according to a knowncode rate, and the sub-MAC header, the data payload, and the FCS aretransmitted at a variable transmission rate depending on a code ratewhich is possible for the transmission. This provides transmitting thePHY header and the common MAC header to be transmitted to a wirelesscommunication apparatus located at a rather remote from the transmissionsource apparatus and suitably transmitting the sub-MAC header and thedata payload, and the FCS to the reception destination apparatus.

FIG. 6 shows a data frame structure according to this example. The dataframe (burst) structure includes sections of a preamble, a PHY header asa physical header, a common MAC (Media Access Control) header, a sub-MACheader, a data payload, and a frame check sequence FCS.

The preamble includes a predetermined known sequence common among allwireless communication apparatuses and is provided for synchronizationof data in an asynchronous data communication.

The PHY header used in a process in the physical layer includes sectionsof: a frame type (eight bits) indicative of the type of the frame in thedata frame (burst) (frame type: eight bits); data of a total data lengthof the burst (total data length: twelve bits); data of a setting ratefor the data payload section (four bits); duration of the data frame(burst) (duration: six bits); and a parity bits (parity: two bits).These numbers of bits are only examples, and the setting rate data forthe data payload section is also indicative of a transmission rate ofthe sub-MAC header.

The MAC header is a header necessary for access control within thenetwork and is divided into a common MAC header and a sub-MAC header inthis example. The common MAC header includes sections of: an address ofa reception apparatus (reception address: six bytes); an address of atransmission apparatus (transmission address: six bytes); a frame typeindicative of the type of this MAC frame (frame type: one byte); a typeof ARQ requested for the confirmation of receiving the data (ARQ type:one byte); a fragment size of the data payload (fragment size: twobytes); and a header check sequence (HCS: four bytes). Here, the numbersof bytes are only examples.

The sub-MAC header includes sections of: a payload length (payload datalength: two bytes); a sequence number (one byte); and a sequence numberin a case of fragmentation (fragment sequence number: one byte). Thenumbers of bytes herein are only examples. If necessary, it is alsopossible to add a header check sequence (HCS: four bytes) (not shown)for detecting an error at the sub-MAC header.

There are ARQ types usable for this wireless communication system suchas a Stop-and-Wait ARQ (SW-ARQ), a Go-Back N ARQ (GBN-ARQ), and aselective repeat ARQ (SR-ARQ).

FIG. 7 shows an example of a data frame in which data payloads aremultiplexed. In this case, the data frame (burst) structure includes,like the general data frame, one preamble, a PHY header (PHYH), and acommon MAC header (CMH). Further, a plurality of sets of sub-MAC headers(SMH), data payloads, and frame check sequences (FCS) are attached. Thestructures of the common MAC header and the sub-MAC header are shown inFIG. 6 for example.

Each data payload is controlled with each sequence number (sequence #1,#2, #3) described in the sub-MAC header, has a data length representedby the payload data length in the sub-MAC header, and has the framecheck sequence (FCS) thereafter for error detection and errorcorrection.

This enables the transmission in which data frames directed to the samedestination are efficiently combined into one burst.

FIG. 8 shows a frame structure of fragment data according to thisexample. The data frame (burst) structure includes, like the generaldata frame, one preamble, a PHY header (PHYH), and a common MAC header(CMH) and further includes a plurality of sets of sub-MAC headers (SMH),data payloads, frame check sequences (FCS) are attached thereto.

The data payload in a sequence, herein, the sequence #1, is divided intofragments (three parts in this example) on the basis of the FragmentSize information and each part is dealt as one data payload.

To each data payload, a sub-MAC header (SMH) and a frame check sequence(FCS) are added to enable error detection and error correction, so thata resending control is provided at this fragment unit.

In this example, because only the last payload has a length less thanthe fragment size, the Payload Length in the sub-MAC header for thefragment #3 indicates this.

FIG. 9 shows an ACK frame format using the common MAC header accordingto this example. The ACK frame is ACK information returned from the datareception destination to the data transmission source to return areception confirmation of the data and is transmitted as shown in FIG.4.

The ACK frame shown in FIG. 9 includes a preamble, a PHY header, and acommon MAC header that has the same structure as the common MAC headerin the general data frame (burst), so that the reception process issimplified.

The ACK frame includes sections of: an address of a reception apparatus(reception address: six bytes); an address of a transmission apparatus(transmission address: six bytes), a frame type indicative of the typeof this MAC frame (frame type: one byte); an ACK sequence number (ACKsequence); bit map information (ACK bit map: two bytes) indicative ofreceived parts in a case of fragmenting the ACK sequence; and a headercheck sequence (HCS: four bytes) for error checking the ACK frame. Here,the numbers of bytes are only examples.

FIG. 10 shows an RTS frame format using the common MAC header accordingto the example. The RTS frame is a transmission requesting signaltransmitted from the data transmission source apparatus to the receptiondestination apparatus before the data transmission and is transmitted asshown in FIG. 4.

The RTS frame shown in FIG. 10 includes a preamble, a PHY header, and acommon MAC header that has the same structure as the common MAC headerin the general data frame (burst), so that the reception process issimplified.

The RTS frame includes sections of: an address of a reception apparatus(reception address: six bytes); an address of a transmission apparatus(transmission address: six bytes); a frame type indicative of the typeof this MAC frame (frame type: one byte); an amount of the queued datato be transmitted (queuing size: two byte); a not-defined region forfuture extension (one byte); and a header check sequence (HCS: fourbytes) for error checking the RTS frame.

FIG. 11 shows a CTS frame format using the common MAC header accordingto the example. The CTS frame is a transmission available conditionsignal and is transmitted from the data reception destination apparatusto the transmission source apparatus before the data transmission, asshown in FIG. 4.

The CTS frame shown in FIG. 11 includes a preamble, a PHY header, and acommon MAC header that has the same structure as the common MAC headerin the general data frame (burst), so that the reception process issimplified.

The CTS frame includes sections of: an address of a reception apparatus(reception address: six bytes); an address of a transmission apparatus(transmission address: six bytes); a frame type indicative of the typeof this MAC frame (frame type: one byte); rate information (availablerate: one byte); a not-defined region for future extension (one byte);and a header check sequence (HCS: four bytes) for error-checking the CTSframe.

FIG. 12 shows an example of a burst in which the control informationframe and the data frame are combined.

In this example, subsequent to a preamble and a PHY header, as a controlinformation frame, an RTS frame is arranged. The RTS frame has thestructure, for example, shown in FIG. 10. After this, a common MACheader, a sub-MAC header, a data payload, and a FCS are arranged as adata frame. The common MAC header and the sub-MAC header may have thestructure shown in FIG. 6.

In the example shown in FIG. 12, the RTS frame is used as a controlinformation frame. However, other frames (ACK frame, CTS frame, and thelike) may be combined with the data frame. Further, in a burst includingsuch a structure, it is possible to use a fixed transmission rate forthe control information frame and the common MAC header and a variabletransmission rate after the sub-MAC header. Further, in FIG. 12, thecontrol frame is added before the data frame. However, the control framemay be attached after the data frame.

FIG. 13 shows a burst in which control frames are multiplexed. In thisexample, after the preamble and the PHY header, as the first controlinformation frame, an ACK frame is arranged, and as the second controlinformation frame, a CTS frame is arranged. The ACK frame and the CTSframe may have the structures shown in FIGS. 9 and 11, respectively.Further, it is also possible to combine it with other controlinformation frames.

Next, a process for the communication operation by the central controlsection 10 in each wireless communication apparatus within the networkwill be described with reference to flow charts shown in FIGS. 14 to 17.First, the general operation of the communication apparatus will bedescribed with the flow chart shown in FIG. 14. It is judged whetherdata is received from the device connected to the interface 11 (stepS1). If the data is received in this judgment, it is judged whether thedata can be wirelessly transmitted (step S2). In this case, for example,beacon information is previously collected from the wirelesscommunication apparatuses therearound and it may be judged that the datatransmission is possible when a wireless communication apparatus capableof communication exists, on the basis of the beacon information.

If the wireless transmission is possible, a header setting process isexecuted (step S3) and the processing returns to step S1. If thetransmission is impossible, the processing directly returns to step S1.

If the data is not received in step S1, it is judged whether there istransmission-waiting data (step S4). If there is transmission-waitingdata, a transmission activation process is executed (step S5). Afterthis, the processing returns to step S1.

In step S4, if there is no transmission-waiting data, it is judgedwhether the wireless communication operation is necessary (step S6). Ifthe wireless communication operation is necessary, the wirelesscommunication operation is executed (step S7) and then, the processingreturns to step S1. Further, in step S6, if the wireless communicationoperation is unnecessary, the processing directly returns step S1.

Next, with reference to the flow chart in FIG. 15, a header settingsubroutine according to this example will be described. First, settingsare made for the common MAC header for data portions (step S11) usingthe address information of the reception destination apparatus, thetransmission source apparatus (its own) address information, and thelike. A sequence number setting is carried out for each transaction(step S12). It is judged whether the fragmentation process is necessary(step S13). If necessary, the fragmentation process is executed to havea predetermined size (step S14). If the fragmentation process isunnecessary, the process in step S14 is not carried out.

Next, the sub-MAC header is set using the sequence number, theinformation of the fragmentation process, a data length, and the like(step S15). The data is set as transmission-waiting data (step S16), andthe processing returns to the main routine.

Next, with reference to the flow chart shown in FIG. 16, a transmissionactivation subroutine will be described. First, settings are made forthe RTS frame before the data transmission (step S21). Then, theapparatus acquires its transmission right on the basis of apredetermined access control (step S22).

When the transmission right is acquired, the RTS frame of which settinghas been done is transmitted (step S23). Further, to receive the CTStransmitted from the reception destination apparatus just after this, asetting is made (step S24) for its own reception region just after thetransmission. Then, the processing terminates the sequential processesand returns to the main routine.

Next, with reference to the flow chart in FIG. 17, the subroutine of thecommunication operation according to this example will be described.First, it is detected whether it is within the setting interval of thereception region (step S31). In a case where it is within the settinginterval, a wireless signal is received (step S32). In a case where apreamble signal is detected in step S33, the rate information for a datapayload portion or the like from the PHY header provided just after thePreamble is stored (step S34).

Further, the common MAC header is received and the data is stored (stepS35). It is confirmed whether the signal is directed to this apparatuswith reference to the address information (step S36). In the step S36,when the Preamble cannot be detected and when the signal is not directedto this apparatus, the processing returns to the step S31 to repeat thisoperation. In the step S36, when the signal is directed to thisapparatus, it is judged which type of the frame is transmitted withreference to the frame type information in the common MAC header.

In a case where it is determined that the type of the frame is a dataframe (step S37), the rate for the data payload is set (step S38) withthe rate information stored in step S34. Next, a reception process forthe data payload is carried out (step S39). Further, in accordance withsuccess or fail in the reception of the data, AKC information isgenerated (step S40). A replying process of the ACK is carried out justafter the reception (step S41), and the processing terminates thesequential processes and returns to the main routine.

In a case where it is determined that the frame is not a data frame inthe step S37, it is judged whether or not the frame is an RTS frame(step S42). In a case where an RTS frame is received, in accordance withthe receiving condition of the RTS frame, an available transmission rateis set for the data section (step S43). Further, the transmission sourceof the RTS frame is set to the reception destination address, and withthese pieces of information, settings are made for the CTS frame (stepS44). Just after this, a replying process of the CTS is performed inStep S45. Next, the receiving region of the data is set in step S46, andthe processing terminates the sequential processes and returns to themain routine.

In a case where it is determined that the frame is not an RTS frame inthe step S42, it is judged whether or not the frame is a CTS frame (stepS47). If the CTS frame corresponding to the RTS frame transmission fromthis apparatus is received, the rate information described at the commonMAC header is referred (step S48). With the stored data, the setting ismade for the data burst (step S49), and an actual data transmissionprocess is performed (step S50). Further, the reception region of theACK is set (step S51), and the processing terminates the sequentialprocess and returns to the main routine.

In a case where it is determined that the frame is not a CTS frame inthe step S47, it is judged whether or not the frame is an ACK frame(step S52). If an ACK frame is received, it is judged whether or notthere is a re-transmission request from the ACK information (step S53).If there is a re-transmission request, the data to be re-transmitted isacquired (step S54), and a setting is made to deal with the data astransmission-waiting data (step S55). The processing terminates thesequential processes and returns to the main routine.

When it is without the setting interval of the reception region in stepS31, when any ACK is not received in step S52, and when re-transmissionis unnecessary in step S53, the processing terminates sequentialprocesses and returns to the main routine.

The above embodiment is described with an example of a specialcommunication apparatus for transmission and reception shown in FIG. 2.However, other structures are possible. For example, a board or a cardfor executing the communication process corresponding to thetransmission section and the reception section in the above-describedexample is attached to a personal computer for various data processes,and software for the corresponding communication control is installed inthe personal computer. The program installed in the data processingapparatus such as the personal computer may be distributed with variousrecording (storing) media such as an optical disc or a memory card ormay be distributed through the Internet.

What is claimed is:
 1. A wireless communication apparatus for wirelesscommunication with another communication apparatus in a predeterminedwireless network, comprising: header generation means for generatingoverhead information defined in a media access control layer with thatsaid overhead information is divided into a first header of informationnecessary for a common access control and a second header of informationnecessary for each payload and executing a process of adding addressinformation to said first header of information necessary for saidcommon access control; and wireless transmission means for attachingsaid headers generated by said header generation means to transmissiondata and transmitting the data.